Most people who have a garage door have accidentally left it open. Leaving the garage door open can have consequences such as; having belongings stolen from the garage or even the house, animals such as snakes can enter the garage to live, and in colder climates pipes can freeze and break. Prior art has come up with devices to fix this issue but are too cumbersome to use. Wires need to be connected, sensors need to be mounted, usually expensive, complicated and time consuming. This led to the idea of creating a device that can be mounted on a garage door, powered off of a battery, work with existing garage door openers, provide a warning before closing the door, and be very simple to install.